The present invention relates to a method of renovating pipes which have two open ends, and wherein any internal coating is removed by passing abrasive agents therethrough.
The pipes to be renovated with the present invention include gas-, steam-, or liquid-carrying pipes which have already been installed. The pipes in question include inlet or outlet pipes for the transport of water or gas in residential, industrial or municipal facilities, including private and industrial sewerage. All pipes of this kind tend to develop deposits which are in particular due to the build-up of scale from water, the formation of rust inside the pipe, precipitation from flowing agents, reaction products of flowing media and substances contained therein in and/or the pipe material, and effects that are combinations thereof. The aforementioned effects cause leakages or substantially reduce the internal diameter of the pipes which in turn interferes with the transport of the flowing medium or even renders such a transport impossible.
The now claimed method of renovating pipes helps avoid a complete replacement of the pipes, a fact that is particularly advantageous when dealing with completely installed sanitary facilities. The pipes of such installations are usually more or less freely accessible once the fittings are removed so that it is possible to apply the claimed cleaning and coating method. It is in any case essential that a pipe be accessible at least two open ends for the individual steps of the method to be carried out. The claimed method does not exclude an at least partial conventional repair of the pipe; the entire pipework can, hence, be partially replaced or partially renovated with the aid of the claimed method.
Methods of the kind in question have been known in the practice for a long time. For an example, refer to European patent application 0 229 134. This European patent application discloses a class-defining method wherein compressed air is used to dry the pipe, remove the deposits at the inside of the pipe, preheat the pipe, and, finally, coat the inside of the pipe. In other words, the method of the invention employs compressed air as such or as a carrier medium to be pressed through the pipe. However, in the practice the use of compressed air is problematic in that compressed air easily destroys already corroded pipes in the area of bends or turns. If the pipe has already leakages, compressed air will escape at the site of leakage and consequently also lead to a corresponding loss of medium carried along by the compressed air. Moreover, compressed air blocks the pipe when the latter already exhibits considerable deposits at its inside thus requiring a considerable amount of work to eliminate the blockage. Parts that were torn away by the compressed air tend to accumulate in bends, and finally lead to a complete blockage of the pipe. This necessitates the pulsed application of compressed air from the other end of the pipe which in turn requires more complex instrumentation and more time and consequently significantly increases the costs.
Further, the known method exhibits the significant disadvantage that it is hardly or not at all possible to detect leakages during the use of the method and/or the application of compressed air. There is, consequently, a risk that the inside is coated despite significant leakages while it is almost impossible to close these leakages. A large leakage or hole is, hence, virtually "stabilized" by the coating and can no longer be effectively closed.
Finally, the known method entails a significant environmental problem in that the particles which are carried along by the compressed air are released into the environment at the open end of the pipe. It is consequently necessary to provide, in addition to the generator for the compressed air at the pipe inlet, special collecting means to collect the particles carried along by the compressed air. In any case, it is impossible to allow the uncontrolled release of the compressed air emerging at the other open end into the environment. This in turn again considerably increases the amount of instrumentation involved.
It is accordingly an object of the present invention to provide a method for renovating pipes where conductive properties are attained which are comparable to those of new pipes while using simple technical means and avoiding pollution of the environment.